When sawing logs, it is desirable that the logs are advanced to the sawing machine in a position such that the logs, as seen from above, are as straight as possible. The same requirement exists also in connection with so-called planreducing of logs, where two opposite sides of the log are made planar as a preparatory step to a subsequent sawing operation. This presents no problem when using so-called log trucks for advancing the logs, since the trucks are constructed to enable the logs to be turned by gripping means on said trucks, before the logs are fed to the saw or plan-reducer.
Log trucks cannot be used to feed logs in modern high-speed saw mills, however, since at each infeed operation the truck must return and grip the rear end of the new log. Consequently, the logs cannot be fed through the saw in end-to-end relationship, as is naturally desired.